Poka Yoke
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This Presentation gives a brief idea on what is Poka yoke and the various types of Poka yoke with examples. It also talks about the short comings of Poka yoke
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Poka Yoke
- 1. 10/11/2015 1 Introduction to Supply Chain Management Dr. Ramzi Hammami Poka Yoke Aditya Ramachandran | Arthur Moreau | Bharadwaj Rai | Jennifer Noizil | Marlene Moser | Kavirajan Prabhu November 10, 2015
- 2. • Introduction • Types of Poka Yoke • How does Poka Yoke Work? • Examples of Poka Yoke • Shortcomings of Poka Yoke • Conclusion 10/11/2015 2 Table of Content
- 3. Just In Time - Philosophy: Elimination of waste & Continuous improvement Defected products do not add value Waste Higher level of inventory to compensate defects Misuse of resources Prevent the manufacturing of defects Basic idea behind Poka Yoke: No human can completely avoid to make mistakes therefore human errors can cause defected products 10/11/2015 3 Introduction
- 4. Tool (mechanism/ device) that helps to achieve zero defects by preventing humans from making mistakes A good Poka Yoke device/ mechanism makes it impossible to make a mistake Formalized by Dr. Shigeo Shingo as part of Toyota Production System 10/11/2015 4 Introduction
- 5. Components of Zero Defect Quality: Point of Origin Inspection: Detect possible mistakes • Elimination of mistakes while they arise • Complete avoiding of mistakes possible 100 % Inspection: Check every single piece not just rely on sample • Every piece runs through simple & easy Poka Yoke device Immediate Feedback: Short reaction time between detection of a deviation and the initiation of corrective actions • Poka Yoke shows mistakes in the sequence that they occur in 10/11/2015 5 Introduction
- 6. Soft Poka Yoke: Warning Alarm Hard Poka Yoke: Control Automatic machine shutdown Proactive: Point of origin inspection Predict mistakes that could occur Zero defect quality fully implemented Reactive: Informative inspection Detect mistakes immediately after process sequence Not 100% elimination, but prevents that defect is passed on 10/11/2015 6 Types of Poka Yoke
- 7. Poka Yoke Methods for detection of errors: Contact method Situations of rapid repetition or environmental problems Identifies abnormalities in product’s shape, size or position with a sensing device Fixed-value method Operator repeats the same activity several times Method that allows the operator to easily track how often an activity was performed Motion-step method Operator performs in sequence several different activities Identify specific motions for each step & create device that detects if each motion is performed 10/11/2015 7 How does Poka Yoke Work?
- 8. Steps of Poka Yoke- Reactive Steps: Step 1: Describe the defect Step 2: Identify where the defect is discovered & where it is made Step 3: Observe the process and detail the steps that differ from the standard sequences Step 4: Identify the contributing conditions (tools, training, etc.) Step 5: Identify the mistake-proof procedures necessary to prevent the defect (Brainstorming with the team) Step 6: Add the new process . Step 7: Test if the process is effective and change it if necessary 10/11/2015 8 How does Poka Yoke Work?
- 9. Mistake Proofing Procedures(Hierarchy): 1. Elimination: Of the step that causes the mistake 2. Replacement: Of the step with a more reliable mistake- proof one 3. Prevention: Change product or process so that mistake is impossible 4. Facilitation: Make the correct action far easier than the mistake 5. Detection: Make mistake obvious for immediate correction 6. Mitigation: Minimize the effects of mistake if it cannot be eliminated 10/11/2015 9 How does Poka Yoke Work?
- 10. 10/11/2015 10 Examples of Poka Yoke Products
- 11. 10/11/2015 11 Examples of Poka Yoke in the Process
- 12. Shortcomings of Poka Yoke Implementation of “new mindset” to workers might be difficult But Poka Yoke should be simple Justification of investment might be difficult Poka Yoke should not be costlier than error correction The Poka Yoke device can be inappropriate or ineffective Testing of Poka Yoke is necessary Poka Yoke might add additional time to the process But Poka Yoke saves time due to prevention of defects Whole production process is stopped if Poka Yoke detects mistake But this way the mistake is not passed on in the process 10/11/2015 12 Shortcomings of Poka Yoke
- 13. Poka Yoke prevents/ detects human errors at their roots Understand why people make errors Analyze where the errors occur (or might occur) Analyse what root causes contribute to them Poka Yoke: Is Simple & very effective due to the 100% inspection 10/11/2015 13 Conclusion
- 14. 10/11/2015 14 Thank You For Your Attention! Any Qustions?
Notas del editor
- To connect our Topic Poka Yoke to the content of the class I want to remind you of the Just In Time Philosophy which is about the elimination of waste & continuous improvement According to this I want to highlight defected products- because they do not and value and are therefore waste, this is due to the higher level of inventory that is necessary to compensate for defected products and due to the misuse of the resources. Therefore the manufacturing of defects need to be prevented. The Basic Idea behind Poka Yoke is that no human can completely avoid to make mistakes because it is natural and therefore human errors can cause defected products.
- Poka Yoke is Japanese and means mistake proofing. It is a tool (either a mechanism or a device) that helps to achieve zero defects by preventing humans from making mistakes. This can be the operators or assemblers during the production process, but also the end customers (if the Product itself is Poka Yoke) The sentence “A good Poka Yoke device/ mechanism makes it impossible to make a mistake” shows, that the System or Product should be improved in a way that it does not allow the humans to make a mistake. Like this errors are kept from becoming defects. It was formalized by Dr. Shigeo Shingo as part of the Toyota Production System.
- To give you some background I want to show you the components of Zero Defect Quality: Point of Origin Inspection (Source inspection) Detect possible mistakes Elimination of mistakes while they arise Complete avoiding of mistakes possible 100 % Inspection Possible to check every single piece not just rely on samples Every piece runs through simple & easy Poka Yoke device Immediate Feedback Short reaction time between detection of a deviation and the initiation of corrective actions Poka Yoke shows mistakes in the sequence that they occur in immediate correction possible
- Soft Poka Yoke: Alarm signal in the car if the car is driving and the seatbelt is not pluged in to remind the driver of wearing the seat belt Hard Poka Yoke: Safety bar at lawn mower machine shuts down to prevent that the lawn mower will drive on when e.g. the operator falls. And also the distinction between: Proactive: predict mistakes that could occur Point of Origin inspection (fully implemented zero defect quality) Reactive: detect mistakes that occurred Informative inspection (Not 100% elimination of all defects but effective in preventing defects from being passed to next process.
- Each method can be used in a control system or a warning system. Each method uses a different process prevention approach for dealing with irregularities. Contact method: Situations of rapid repetition or environmental problems (e.g. poor lightening, or extreme heat the operator is distracted) Identifies abnormalities in product’s shape or size with a sensing device Example: a chute that detects and removes upside-down or reversed parts, or an in-line gauge that removes dimensional defects and reroutes them to a defect lockbox. Fixed-value method: Operator repeats the same activity several times Method that allows the operator to easily track how often an activity was performed Example: Use of packaged material in the exact (fixed) quantities needed to complete the process (bolts stored in containers of six operator could easily see when the process was still incomplete as the box would still contain one or more bolts). Motion-step method: Operator performs in sequence several different activities Identify specific motions for each step & create device that detects if each motion is performed Example: Device: Senses when all required components are present at the start of the process for each unit detects when each component is removed from its depenser if component is not removed it alerts the operator before he can move to the next step.
- Steps of Poka Yoka in case of the reactive effort (mistake already occured and needs to be detected)
- How does Poka Yoke work 1. Elimination Eliminate the step that causes the mistake Remove Non-Value Added activities - Redesign the product or process 2. Replacement: Replace the step with a more reliable mistake- proof one Automation of repetitive motion activities 3. Prevention: Change product or process so that mistake is impossible Physical barrier or fit to prevent undesired action 4. Facilitation: Make the correct action far easier than the mistake Visual controls like colour coding, labels, lines, and signs 5. Detection: Make mistakes obvious for immediate correction Sensors, limit switches, light sensors 6. Mitigation: Minimize the effects of mistakes For when the mistake cannot be eliminated
- Hard: Gas cap is attached with tether does not get lost Hard: USB cable: You can only connect a USB device to a USB host because the ends of the cable have two different forms (input & output) Hard: Microwave shuts down when you upen the door Hard: Sim Card has a certain shape so that it is impossibel to place it in the wrong way Soft: Pan has a red point in the middle that will glow to remind the user the pan is hot
- Poka Yoke devices can be applied within any process Hard: Device only allows the standard size to pass through it Hard: Rotation of machine will only start when saftey guard is pulled on Soft: Color coding to indicate the different sizes of the bolts Hard: Machine is only working if operator steps on the sensor pad or if he uses both hands to operate a machine
- Implementation of “new mindset” to workers might be difficult But Poka Yoke should be simple Justification of investment might be difficult Poka Yoke should not be costlier than error correction The Poka Yoke device can be inappropriate or ineffective Testing of Poka Yoke is necessary Poka Yoke might add additional time to the process But Poka Yoke saves time due to prevention of defects Whole production process is stopped if Poka Yoke detects mistake But this way the mistake is not passed on in the process
- Poka Yoke prevents/ detects human errors at their roots Understand why people make errors Analyze where the errors occur (or might occur) Analyse what root causes contribute to them Poka Yoke: Is Simple & very effective due to the 100% inspection
- Thank You for your attention! Do you have any questions?
- Error: When any condition necessary for successful processing is wrong or absent Reasons for errors: Language Barriers- (i.e. English as a second language) Misunderstanding instruction or procedure Errors made through lack of experience etc. Forgetfulness Misunderstanding Wrong identification Lack of experience Willful (ignoring rules or procedure) Inadvertent or sloppiness Slowliness Lack of standardization Surprise (unexpected machine operation, etc.) Intentional (sabotage)